Piles are often used to resist vertical and lateral loads when shallow foundations are inadequate or uneconomical. A critical part in designing pile foundations is the pile-to-cap connection. When a moment resisting connection is desired, reinforcement is typically used between the pile and the cap. A pile-to-cap connection with sufficient pile embedment depth, however, may provide similar results. One model that is currently used to determine the capacity of a pile-to-cap connection was developed by Marcakis and Mitchell for steel members embedded in concrete. This model considers an embedment mechanism that resists rotation at the connection. Recent testing has shown, however, that this model is conservative and that additional mechanisms contribute to the strength of the connection. An experimental study was conducted to investigate pile-to-cap connections for pipe piles without reinforcement. Three pile-to-cap specimens with varying pile embedment depth were loaded laterally to failure. The results from the testing confirm that pile-to-cap connections with shallow pile embedment depth have significant stiffness. An improved model was developed to estimate elastic and ultimate capacities of embedded connections. In addition to the embedment mechanism used by Marcakis and Mitchell, this model includes a bearing mechanism at the end of the pile. For pile-to-cap connections with a large pile bearing area to pile embedment depth ratio, this bearing mechanism provides more strength than the embedment mechanism. For pile-to-cap connections with a small pile bearing area to pile embedment depth ratio, this bearing mechanism has little contribution to the strength of the connection.



College and Department

Ira A. Fulton College of Engineering and Technology; Civil and Environmental Engineering



Date Submitted


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pile, pile-to-cap, embedment, foundation